Humidifier device and method of forming the same

ABSTRACT

A humidifier of the present invention includes a bundle of hollow porous tubes made of synthetic material disposed in a housing having a plurality of inlet and outlet ports. The humidifier of the present invention is used to control humidity in a fuel cell and is used in various industrial applications. A method of producing the humidifier is disclosed herein.

RELATED APPLICATIONS

This non-provisional application claims priority to a provisional application Ser. No. 60/817,991 filed on Jun. 30, 2006 and incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a humidifier for a fuel cell systems, and specifically to the humidifier utilizing hollow fibers and a method of forming the same.

BACKGROUND OF THE INVENTION

A typical fuel cell presents is an electrochemical energy conversion device for producing electricity from external supplies of fuel and oxidant in the presence of an electrolyte. Generally, the reactants flow in and reaction products flow out while the electrolyte remains in the fuel cell. One of the benefits of the fuel cell over, for example, a battery, is the ability of the fuel cell to operate virtually continuously as long as necessary flows are maintained. Unlike the battery, which store electrical energy chemically in a closed system, the fuel cells consume reactants, which must be replenished. Additionally, while the electrodes within the battery react and change as a battery is charged or discharged, the electrodes of the fuel cell are catalytic and relatively stable.

Alluding to the above, the fuel cells generate electrical power that can be used in a variety of applications. One of the most reliable types of the fuel cell is a proton exchange membrane (PEM) fuel cell. The core element of modern PEM fuel cell is the membrane electrode assembly (MEA) including the ion exchange membrane, which acts as a solid electrolyte and thin catalytic layers deposed on both sides of the membrane acting as anode and cathode electrodes. The PEM fuel cell gas diffusion layers (GDL) support MEA and distribute reactants to the electrodes and flow plates directing reactants and an electrical current. To produce electricity through an electrochemical reaction, hydrogen-rich fuel is supplied to the anode (mainly the hydrogen) and the oxidant gas (mainly the air) is supplied to the cathode.

An electrochemical reaction between hydrogen and the oxygen contained in the air produces the electrical current, water and heat as the reaction products. Water is removed from the cathode to make the catalytic layer accessible for the oxygen. On the other hand, the air introduced to the cathode supposed to be rich in water vapor to prevent drying out of the PEM, which results in failure of the fuel cell failure. In some fuel cell systems the hydrogen, delivered to the anode, is also subject for humidification. A humidifier of the fuel cell presents the main device to keep the correct water balance in the fuel cell, thereby transferring the moisture across an internal membrane permeable for water molecules from water carrier to gas introduced into the fuel cell as the reactant. The major sources of water intended for the humidification are DI water or an exhaust gas from the fuel cell cathode.

Alluding to the above, a dialyzer, as know to those skilled in the art, utilizes membranes of various designs, fabricated from polysulfone, polycarbonate, polyamide, and the like. The high chemical stability and sufficient mechanical durability of these materials allow to the differential pressure commonly used in the hemodialysis, which can exceed 10 psi thereby allowing to re-process the reusable dialyzer. The membrane presents a micro-porous structure and does not expand to the same degree as hygroscopic membranes because water fills the voids in the material instead of creating swelling or volume displacement.

For the humidification process the most acceptable dialysis membrane is low flux type having the lowest permeability (10 ml/hr/mmHg) to prevent the mixing the reactant with liquid water, (in case of humidification by means of water) or with humid exhaust gas (gas to gas humidification). A dialyzer can be modified in a manner that it can be applicable as a humidifier for fuel cell systems and other applications wherein air humidification is required. The use of a properly modified dialyzer advantageous in that it is a widely distributed and inexpensive device. A humidifier design is highly dependable on the application of a fuel cell system, its concept, etc.

The art is replete with various humidifier designs as taught by the U.S. Pat. No. 4,801,385 to Sachtler et al. and the U.S. Pat. No. 4,381,267 to Jackson. One of the most effective membrane package is presented by a multitude of hollow tubes arranged in a bundle inserted into a housing wherein the ends of the tubes encapsulated in a resin. The typical membrane type used in the fuel cell humidifiers is Nafion®. Water transport between fluid streams in these humidifiers occurs via a hygroscopic polymer, whose water absorption properties are due to chemical affinity. Although effective humidification is accomplished with these devices, several detriments exist to their use. Among these is the issue of polymer expansion with water uptake, which results in a fragile, failure prone device. During operation, Nafion® polymer membrane expands and contracts as varying levels of humidity are absorbed, which leads to detachment of the tubes from the bonding resin. The pressure difference between fluid streams can results in cracks, tears, fractures and collapsing the tubes. Maximal differential pressure specified for the humidifiers based on Nafion® can not exceed 2 psi, which is in the range of possible pressure fluctuation.

As such, there is a constant need in the area of a humidifiers for an improved design and a method of forming the humidifier thereby eliminating problems associated with current designs of prior art humidifiers.

SUMMARY OF THE INVENTION

A humidifier device (the humidifier) of the present invention is used with a fuel cell for balancing fluids therein. The humidifier includes a tubular housing presenting a central axis and terminal ends and a pair of housing ports defined therein. A pair of caps cover each of the terminal ends with each cap being exposed to a cap port. A plurality of polymer tubes presenting terminal openings are adjacent one and another and are disposed in the tubular housing for processing and balancing fluids introduced therein. A covering element formed from an epoxy solution at least partially extends into each of the terminal openings of each polymer tube. The covering element also covers exterior of each said polymer tube at the terminal openings. Each covering element of each polymer tube is homogeneously connected with one another for withstanding pressure of fluids in each polymer tube as the polymer tubes process and balance fluids introduced therein.

In another aspect of the present invention, a medical device for treating a human is disclosed. The medical device processes fluids, such as for example blood, from the human body with a dialyzing solution thereby treating fluids before fluids are re-introduces to the human body. The medical device includes a semipermeable membrane presenting a central axis and having terminal ends and a pair of housing ports and a pair of caps covering each of the terminal ends with each cap exposed to a cap port.

A plurality of polymer tubes each presenting terminal openings are adjacent one and another and are disposed in the semipermeable membrane for processing and balancing fluids and the dialyzing solution introduced therein. A covering element at least partially extends into each of the terminal openings of each the polymer tube and covers at least part of each polymer tube at the terminal openings for withstanding pressure of fluids and the dialyzing solution in each polymer tube as the polymer tubes process and balance fluids and the dialysis solution introduced therein. Dializer fittings and connected to the tubular housing are designed to flow the dialyzing solution and blood.

An apparatus for fabricating the aforementioned humidifier and the medical device is also disclosed in the present invention. The apparatus has at least a frame for engaging the housing of the humidifier and the medical device at the respective terminal ends. The frame presents opposite inlet ports exposed to the terminal openings of the polymer tubes. At least one container for holding a solution, such as an epoxy adhesive, is connected to the frame and is fluidly communicated to each of the opposite inlet ports for transferring the solution to the housing through the terminal ends. An activator is connected to the frame for rotating the same about a rotational axis thereby generating a centrifugal force thereby at least partially introducing the solution internally into each of the terminal openings of the polymer tube for bonding the polymer tubes.

The polymer tubes of the inventive humidifier present invention are hollow fibers, having water-permeable and micro-pores structure and are fabricated from polysulfone, polycarbonate, polyamide, and the like, adaptable to exchange humidity between two fluid streams, i.e. gas to gas or liquid to gas. The water permeability of the membrane is not higher than 10 ml/hr/mmHg to minimize the leakage of water carrier (DI water, humid gas) into the gas stream subject for the humidification.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a cross sectional view of an inventive humidifier;

FIG. 2 is a cross sectional view of an alternative embodiment of the humidifier shown in FIG. 1;

FIG. 3 is a cross sectional view of a second alternative embodiment of the humidifier of FIG. 1;

FIG. 4 is a schematic view of fiber tubes of the humidifier interconnected by a pair of retaining rings, shown in a cross section, to form a bundle or a unitary member;

FIG. 5A shows the bundle of FIG. 4 and a container with epoxy adhesive adjacent the bundle is for briefly introduced into the epoxy adhesive before the humidifier is completely fabricated;

FIG. 5B is a cross sectional view of the fiber tubes before introduction into the epoxy adhesive;

FIG. 6A shows the bundle of FIG. 4 wherein terminal ends of the bundle are briefly introduced into the epoxy adhesive before the humidifier is completely fabricated;

FIG. 6B is a cross sectional view of the fiber tubes being introduced into the epoxy adhesive;

FIG. 7A shows the bundle of FIG. 4 wherein terminal ends of the bundle are removed from the epoxy adhesive after the same are briefly introduced into the epoxy adhesive;

FIG. 7B is a cross sectional view of the fiber tubes after the terminal ends had been introduced into the epoxy adhesive;

FIGS. 8 through 10 illustrate a cross sectional view of an apparatus for forming the humidifier of the present invention;

FIG. 11A is a cross sectional view of the humidifier with the terminal ends of the fiber tubes being completely encapsulated by the epoxy adhesive;

FIG. 11B is a cross sectional view of terminal ends of the fiber tubes of FIG. 11A;

FIG. 12A is a cross sectional view of the humidifier with the terminal ends of the fiber tubes being completely encapsulated by the epoxy adhesive;

FIG. 12B is a cross sectional view of terminal ends of the fiber tubes of FIG. 12A; and

FIG. 13 is perspective view of a medical device incorporating the humidifier of the present invention for treating a patient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figures, wherein like numerals indicate like or corresponding parts, a humidifier device (the humidifier) of the present invention is generally shown at 10. The humidifier 10 is used with a fuel cell (not shown) for balancing fluids therein. The humidifier 10 includes a tubular housing, generally indicated at 12, presenting a central axis A and terminal ends 14 and 16. A pair of housing ports 18 and 20 are defined therein.

Alluding to the above, the tubular housing 12 presents an annular wall 24 integrally extending a main portion 26 for aligning a unitary member, generally indicated at 28. The tubular housing 12 further defined a pair of cap engaging portion 30 and 31. A pair of fittings 32 and 34 are integral with and extend generally perpendicular to the central axis A from the main portion 26 at each of the terminal ends 36 and 38 of the tubular housing 12. Each fitting 32 and 34 further extend to the cap engaging portions 30 and 31. A pair of caps 38 and 40 cover each of the terminal ends 36 and 38. Each cap 38 and 40 are exposed to respective cap ports 42 and 44. The caps 38 and 40 are mechanically connected to the respective cap engaging portions 30 and 31.

Alluding to the above, FIGS. 2 and 3 show alternative embodiments of the present invention, generally shown at 200 and 300, respectively. The humidifiers 200 and 300 present the cap ports 202, 204, and 302 and 304 being mechanically engaged with the respective caps 206, 208 and 306 and 308. The humidifiers 200 and 300 also present the fittings 210, 212, and 310 and 312 being mechanically engaged and/or bonded with the main portion of the respective humidifiers 200 and 300. The mechanical connection defined between the aforementioned elements illustrated in FIGS. 2 and 3 are not intended to limit the scope of the present invention.

The unitary member 28 is defined by a plurality of polymer tubes, generally indicated at 50 being adjacent one and another and disposed in the tubular housing 12 for processing and balancing fluids introduced therein. The polymer tubes 50 of the inventive humidifier 10 acting as a membrane, are hollow fibers, having water-permeable and micro-pores structure and are fabricated from polysulfone, polycarbonate, polyamide, and the like, adaptable to exchange humidity between two fluid streams, i.e. gas to gas or liquid to gas. The water permeability of the membrane is not higher than 10 ml/hr/mmHg to minimize the leakage of water carrier (DI water, humid gas) into the gas stream subject for the humidification.

A pair of retainer rings 51 and 53 keep the tubes 50 as a unitary member before the tubes 50 are placed inside the housing 12. The rings 51 and 53 peripherally affix the polymer tubes 50 about the terminal opening thereby expanding the polymer tubes 50 extending beyond the rings 51 and 53 with the polymer tubes 50 abutting the tubular housing 12 thereby eliminating gaps between the tubular housing 12 and the polymer tubes 50 for balancing fluids therethrough. The tubes 50 are bonded by a covering element or sealing compound, generally indicated at 60 in such a fashion to exposed internal capillaries of the tubes 50 to opposite chambers 62 and 64 defined between the sealing compounds 60 and the caps 38 and 40. The covering element 60 is formed from an epoxy compound and at least partially extends into each of the terminal openings 64 of each polymer tube 50. The covering element 60 also covers exterior of each polymer tube 50 at the terminal openings, as best illustrated in FIGS. 6A, 6B, 7A, and 7B. Each covering element 60 of each polymer tube 50 is homogeneously connected with one another for withstanding pressure of fluids in each polymer tube 50 as the polymer tubes 50 process and balance fluids introduced therein.

As illustrated in FIG. 13, the humidifier 10 is incorporated into a medical device, such as, for example, a dialysis machine 70 for treating a human. The dialysis machine 70 processes fluids, such as for example blood, from the human body with a dialyzing solution thereby treating fluids before fluids are re-introduces to the human body. In particular, the dialysis machine 70 mixes and monitors the dialysate, i.e. fluid that helps remove the unwanted waste products from human's blood and helps get your electrolytes and minerals to their proper levels in the human's body. The dialysis machine 70 holds a plastic jug device 71 hold the liquids used to mix the dialysate. The dialysis machine 70 mixes the dialysate, which is made up of an acidified solution, bicarbonate and purified water. The acidified solution contains electrolytes and minerals.

While the human 72 is dialyzing, dialysate and blood flow through a semipermeable membrane 72 or dyalizer catridge presented by the polymer tubes 50 as set forth above, adaptable to withstand pressure of fluids and the dialyzing solution in each polymer tube 50 as the polymer tubes 50 process and balance fluids and the dialysis solution introduced therein. having identical structural characteristics as the humidifier 10 presents. Fresh dialysate from the dialysis machine 70 enters the dialyzer catridge 72 throughout your treatment. Impurities are filtered out of your blood into the dialysate. Dialysate containing unwanted waste products and excess electrolytes leave the dialyzer catridge 72 and are washed down the drain (not shown). A pair of tubes 74 are cooperable with the dyalizer catridge 72 for circulating the dialyzing solution and blood to and from the human body. Dializer fittings 76 and 78 are connected to the dyalizer catridge 72 and are designed to flow the dialyzing solution and blood.

An apparatus for fabricating the aforementioned humidifier 10 is also disclosed in the present invention and is generally shown at 80 in FIGS. 8 through 10. The apparatus 80 has at least one frame, generally indicated at 82, for engaging the housing 12 of the humidifier 10 at the respective terminal ends. The frame 82 presents opposite inlet ports 84 and 86 exposed to the terminal openings of the polymer tubes 50. A pair of containers 88 and 90 for holding a solution 92, such as an epoxy adhesive, are connected to the frame 82 and is fluidly communicated to each of the opposite inlet ports 84 and 86 for transferring the solution 92 to the housing 12 through the terminal ends. The frame 82 may include several parts, such as, for example, the opposite inlet ports 84 and 86.

Alternatively, the frame may present a unitary piece (not shown). An activator 100 is connected to the frame 82 or to the housing 12 for rotating the same about a rotational axis B thereby generating a centrifugal force to introduce the solution 92 internally into each of the terminal openings of the polymer tube 50 through pipe conduit members 102 and 104 thereby bonding the polymer tubes 50.

The process of forming the humidifier 10 for the medical device 70 is clearly illustrated in FIGS. 4 through 7B and begins with affixing the tubes 50 with the aforementioned retainer rings 51 and 53 to form a bundle or the unitary piece thereby forming a dense package of the tubes 50 to prevent the tubes 50 from being loose. Each terminal end of the tubes 50 is then briefly applied into a second epoxy solution 94 hold in a container 96 to fill tips of internal capillaries 98 of the tubes 50 with the epoxy solution 94 whereby the retainer rings 51 and 53 restricts submerging the hollow polymer tubes 50 into the epoxy solution 94, as best shown in FIGS. 6A and 6B.

Alluding to the above, the duration of the exposure of the terminal ends of the tubes 50 into the epoxy solution 94 depends on the viscosity of the epoxy solution 94 and the capillary capability to force the epoxy solution 94 into the internal capillaries 98 and, is generally between 2 and 5 seconds, without limiting the scope of the present invention. The expose of the terminal ends of the tubes 50 to the epoxy solution 94 is necessary for the penetration of the epoxy solution 94 in the tubes 50 without entering the tubes 50 beyond the level the rings 51 and 53, as shown in FIG. 6A. FIGS. 7A and 7B illustrate the next stage of the method also knows as curing the epoxy solution 94 to clogg the internal capillaries 98.

FIGS. 8 through 10 illustrate the next step of the formation of the humidifier 10. The housing 12 with the tubes 50 disposed therein is placed into the frame 82 of the apparatus 80. As the frame 82 is rotated about the rotational axis B by the activator 100, the centrifugal force generated thereby forces the solution 92 internally into each of the terminal openings of the polymer tube 50 through the pipe conduit members 102 and 104 thereby bonding the polymer tubes 50 presents opposite inlet ports 84 and 86 exposed to the terminal openings of the polymer tubes 50. The volume of the solution 92 placed in the containers 88 and 90 is predetermined based upon configuration and volume of the humidifier 10. The application of the centrifugal force continues until the curing process of the epoxy is complete. All of the aforementioned components of the apparatus 80 are fabricated from a non-adhesive to the epoxy solution material which allows them to be reusable after the housing 12 and the tubes 50 disposed therein are removed from the apparatus 80.

While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. A humidifier device for a fuel cell adaptable for balancing fluids therein, said humidifier comprising: a tubular housing presenting a central axis and having terminal ends and a pair of housing ports; a pair of caps covering each of said terminal ends with each said cap exposed to a cap port; a plurality of polymer tubes each presenting terminal openings with said polymer tubes being adjacent one and another and disposed in said tubular housing for processing and balancing fluids introduced therein thereby controlling humidity inside said humidifier; and a pair of rings for peripherally affixing said plurality of polymer tubes about said terminal opening thereby expanding said polymer tubes extending beyond said rings with said polymer tubes abutting said tubular housing thereby eliminating gaps between said tubular housing and said polymer tubes for balancing fluids therethrough.
 2. A humidifier device as set forth in claim 1 including an adhesive compound at least partially extending internally into each of said terminal openings of each said polymer tube and externally covering at least part of each said polymer tubes at said terminal openings for withstanding pressure of fluids in each said polymer tubes as said polymer tubes process and balance fluids introduced therein.
 3. A humidifier device as set forth in claim 2 wherein said adhesive compound is epoxy adhesive.
 4. A humidifier device as set forth in claim 4 wherein said tubular housing presents an annular wall integrally extending a main portion for aligning said unitary member and a pair of fittings extending generally perpendicular to said central axis at each of said terminal ends.
 5. A humidifier device as set forth in claim 4 wherein each said pair of fittings further extend to cap engaging portions, respectively, extending generally parallel said central axis with each of said rings disposed between said polymer tubes forming a unitary member and each said cap engaging portions with each said cap engaging portions presenting a mechanical connection with said caps.
 6. A humidifier device as set forth in claim 1 including a plurality of fitting tubes mechanically engaged with said housing ports and said cap port for receiving fluids into said and releasing fluid from said humidifier device. 